Over the last few decades, the use of computers has become widespread in business, education and at home. Modern computers are controllable by way of graphical user interfaces (GUIs) which allow a user to control the computer simply by manipulating a cursor to select commands from lists of alternatives displayed in pull-down menus on the screen of the computer.
The cursors employed in GUIs are designed to be controlled by a pointing device rather than a keyboard, although in practice control is often duplicated on the keyboard so that the computer can still be controlled if the pointing device should fail. Various pointing devices have been developed for control of a cursor in a GUI environment. The pointing devices are also typically provided with one or more switches or buttons for user selection of system functions. Separate switching modules may also be provided.
All of these previously proposed pointing devices may easily be manipulated by an able-bodied user to control a cursor in a GUI, and thus to control a computer. These modern computers can be controlled to perform a large number of functions such as speech replication and global communication through the internet and through modern to modern connections.
Given the great utility of modern computers, it would be highly desirable if they could be effectively utilised by mentally and physically disabled persons to perform a variety of different functions. To this end, various pointing devices have been developed which cater for the special needs of disabled users. These devices provide improved mechanisms for the control of an on-screen cursor, but they typically do not address the problems associated with the user selection of computer system functions.
For example, some mental and physical disabilities are such that the disabled person is incapable of illustrating the fine motor control necessary to depress keys of a keyboard or to depress buttons on a conventional pointing device to select functions of, or perform tasks on, a computer system. Other disabled persons suffer from problems associated with hand shake, for example, that cause a repeated depression of a button when they only wanted to press the button once. As a consequence of this, these disabled persons can be unable to effectively operate modern GUI-driven computers.